A novel transient enhanced diffusion model of phosphorus during shallow junction formation

Abstract

High-dose ion implantation and low temperature annealing are one of the key technologies for shallow junction fabrication in quarter-micron CMOS VLSIs. It is well known that transient enhanced diffusion (TED) of implanted dopants dominates in diffusion mechanism at low temperature furnace annealing and RTA (Rapid Thermal Annealing). We reported an empirical compact model of TED which describes its dependency on implant doses and annealing temperature. However, the model assumes effective diffusivity during the 10 minutes in furnace annealing, therefore it fails to describe time-dependent TED effect such as short-time RTA and ramping-effect in furnace annealing. In this work, a new study on transient enhanced diffusion is discussed, which is focused on the RTA process for phosphorus diffusion. The dependency of annealing time on TED phenomenon is newly characterized as parameters of annealing temperature and implant dose in the new model.